1. Field of the Invention
The present invention relates to a system and method for monitoring a control system parameter.
2. Background Art
A number of strategies for detection and diagnosis of anomalous or irregular operation of the control computer or system sensors and/or actuators have been developed. One approach to detect anomalous operation uses a monitor to provide an alternative determination (preferably independently) of a parameter value, acceptable range, minimum, or maximum based on current operating conditions. If the parameter value determined by the control system is outside of the acceptable range or differs significantly from that determined by the monitor, the system might provide a warning and/or initiate an alternative control strategy, for example. However, initiating an alternative control strategy may adversely impact system performance. As such, it is desirable to provide detection of anomalous operation without any incorrect or false detection that may adversely impact system operation, to avoid any decrease in performance that might otherwise lead to customer complaints and associated warranty costs.
One application for a parameter monitor is in controlling a vehicle and/or vehicle systems and subsystems, such as an internal combustion engine. For example, engines having an electronic throttle control (ETC) system have no mechanical link between the accelerator pedal operated by the driver, and the throttle, which generally controls engine output power. These systems may use a parameter monitor to detect anomalous operation of the throttle control system. In an effort to detect every occurrence of certain anomalous conditions, the present inventor has recognized that the parameter monitor may incorrectly trigger alternative control strategies in response to deviations of one or more system components or models, for example, which are within the expected tolerance of those elements.